1. Field of the Invention
The present invention is related to a container for storing semiconductor components or reticles, and more particularly, to a reticle pod, in which sensing apparatuses (especially pressure sensors) are disposed to determine whether the reticle pod is stably fastened.
2. Description of the Prior Art
In the rapidly developing modern semiconductor technology, optical lithography tool plays an important role. The pattern definition relies fully on optical lithography technology. In the application of optical lithography tool related to semiconductors, pre-designed circuit paths are fabricated as light-transparent reticle in specific form. Basing on the principle of exposure, after light from the light source passes through the reticle and is projected on a silicon wafer, specific circuit pattern can be exposed on the silicon wafer.
The industry trend is toward smaller chip dimensions and/or production of higher density logic chips at smaller linewidth on larger wafers. Apparently, both the degree of how precisely a reticle can be projected with the pattern and the degree of how exactly the pattern can be reproduced on the surface of a wafer affect the quality of a final semiconductor product. The resolution with which the pattern is reproduced on a wafer is determined by the wavelength of UV light used to project on the surface of wafer covered with photoresist. DUV (deep ultraviolet light) with the wavelength of 193 nm is used in current lithography tool, the minimum feature size compatible with which is 100 nm. At present lithography tool using EUV (extreme ultraviolet light) with the wavelength of 157 nm has been developed so that the resolution of feature size can be smaller than 70 nm.
Thus it is very important to prevent the surface of the reticle from being contaminated by any contaminant, since the contaminant can cause damage to the surface or distortion of pattern projected onto the photoresist layer in the process and thus result in final product of poor quality. Above the surface of a conventional reticle is a thin, transparent pellicle that stretches over a frame, and the functions of the pellicle are to seal off the reticle from external contaminants and to reduce printing defects that may be caused by contaminants moving to the pattern template. However, whereas reflection on the patternized surface is used in EUV lithography, transmission is used in DUV lithography. At present, the conventional art is still not able to provide pellicle material that can be penetrated by EUV. Therefore, it is easier for reflection reticles in EUV lithography to be contaminated and damaged to a higher degree than reticles in conventional lithography. From this situation thus arise the requirement for containers to be used in EUV lithography for receiving, storing, transporting, and carrying wafer with reinforced functions.
Consequently, in order to reduce contamination generated during the process of storing, manufacturing, and transporting, the isolation technology of the prior art that has been developed employs a reticle pod, in which an inner container is used for carrying the reticle and an outer container for fastening the inner container therein, referring to FIG. 6. As shown in FIG. 6, the lower cover c and the upper cover d of an inner container cover the reticle e and fasten the reticle e within the inner container, and then the lower cover a and the upper cover b of an outer container cover the inner container and fasten the inner container within the outer container. During the exposure process of EUV lithography, in the lithography tool, the inner container needs to be first taken out of the outer container and then the reticle is taken out of the inner container for the exposure to be performed. Thus, when the exposure process is performed, it is necessary for the inner container and the outer container to be separated from each other or to be joined together; however, during the exposure process, the operating staff is not able to know whether the inner container still remains in the non-transparent outer container or whether the inner container has really been tightly covered. Under such circumstance of uncertainty, it is highly possible for the inner container to fall or get lost, which then results in damage of reticle and thus increase of cost. In consideration of this, the present invention provides a reticle pod in which pressure between the outer container and the inner container can be detected.